Can anyone explain

[gattocattivo]

Can we have a thread for Q&A about things you want to know and other MNers might be able to explain?

I was reading about a women who gave birth to twins and it took a long time and various tests to determine whether they were identical or not. I always thought it was straightforward and that identical twins share a placenta. How come it's not always that simple?

Don’t know the answer to yours. But I’ve always wondered about if our body completely renews itself (not sure how to word it better) every 7 years or whatever it is, why don’t tattooes completely disappear?

Ooo that’s a good question.

I don’t know but my guess would be that even those the cells around the dye renew the dye molecules remain iyswim?

I have MCDA twins (own sacs, one placenta, identical), then you can have MOMO twins (one sac, one placenta, identical), rare and really risky because of cord entanglement.

DCDA (two sacs, two placentas), non identical.

ID twins come from one egg that solid. It can be really hard to tell on a scan of there is a membrane in the placenta separating them so they can appear DCDA but are actually MCDA.

One egg that splits!

@nearlyspringyay thanks. I didn't realise it can be so difficult to determine on ultrasound but that explains it.